Fluorosulfation of fluoroalkyl halides

The basic characteristics of fluorosulfation of fluoroalkylhalides (effect of the structure of the polyfluoroalkyl, nature of the halogen, acid catalysis, etc.) with halogen fluorosulfates and peroxydisulfuryl difluoride were investigated. A mechanism was proposed for formation of fluorosulfonic acid fluoroalkyl esters based on the experimental and quantum chemical data.A. N. Nesmeyanov Institute of Organoelemental Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1718–1732, August, 1992.     

Reactions of highly electrophilic polyfluorocarbonyl compounds with primary arylamines

C-Hydroxyalkylation of primary arylamines by highly electrophilic polyfluorocarbonyl compounds results from the direct reaction of the initial reagents and is competitively inhibited by equilibrium N-hydroxyalkylation. The presence of steric hindrances to the formation of N-hydroxyalkylation products and an increase in the ring C-nucleophilicity facilitate the C-hydroxyalkylation reaction.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 383–389, February, 1990.     

Maximization of the lift/drag ratio of airfoils with a turbulent boundary layer

The problem of seeking the maximum life/drag ratio for airfoils in an incompressible separationless high-Re flow is considered in the turbulent boundary layer approximation. Within the framework of this model, the maximization of the L/D ratio is redwed to the determination of a conditional extremum for a convex functional. An explicit analytical expression for the extremal solution is obtained. The angle-of-attack dependence of the L/D ratio is demonstrated. The global maximum of the L/D ratio is determined. The results are compared with the known data of numerical optimization. Kazan’. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 3, pp. 177–184, May–June, 1998.     

Estimation of performance parameters of a frontal variant of optoacoustic determination with a model system

Using a model system, the applicability of the frontal configuration of optoacoustic spectroscopy in analytical practice is shown. An optoacoustic cell made using layered-prism geometry was designed and tested; it ensures operation with a layer thickness of 20–100 μm and sample volumes of 50–100 μl. Conditions are proposed for determining iron(II) in the form of tris(1,10-phenanthrolinate) with the detection limit of 3 × 10⁻⁷ M, which is less that the detection limit under similar induction conditions and for the same determination procedure using thermal-lens spectrometry (4 × 10⁻⁷ M). The determination has high reproducibility (relative standard deviation for 10⁻⁶ M is 0.005) and expressivity (1 min per sample detection).     

Catalytic asymmetric C-H insertions of rhodium(II) azavinyl carbenes

A highly efficient enantioselective C-H insertion of azavinyl carbenes into unactivated alkanes has been developed. These transition metal carbenes are directly generated from readily available and stable 1-sulfonyl-1,2,3-triazoles in the presence of chiral Rh(II) carboxylates and are used for C-H functionalization of alkanes to access a variety of β-chiral sulfonamides.     

Bis(1,1,1,3,5,5,5-heptafluoro-4-iminopent-2-ene-2-aminato)copper(<Emphasis Type="SmallCaps">ii</Emphasis>) — a new metal-containing matrix in the design of heterospin systems

The first heterospin compounds based on bis(1,1,1,3,5,5,5-heptafluoro-4-iminopent-2-ene-2-aminato)copper(ii) (CuL₂) and nitronyl nitroxide radicals, 2-R-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyls (NIT-R, where R = H, Me, Ph, and 1-methylpyrazol-4-yl), were synthesized and structurally characterized. An important peculiarity of the structure of synthesized solid phases is the formation of a supramolecular structure due to hydrogen bonds between the oxygen atoms of the nitronyl nitroxide fragments of NIT-R and the hydrogen atoms of the NH groups of CuL₂.     

Comparative theoretical and experimental analysis of hydrocarbon σ-radical cations

The structures of σ-radical cations formed by ionization of adamantane, twistane, noradamantane, cubane, 2,4-dehydroadamantane, and protoadamantane were optimized at the B3LYP, B3LYP-D, M06-2X, B3PW91, and MP2 levels of theory using 6-31G(d), 6-311+G(d,p), 6-311+G(3df,2p), cc-PVDZ, and cc-PVTZ basis sets. On the whole, single-configuration approximations consistently describe the structure and transformations of the examined σ-radical cations. The best correlations (r = 0.97–0.98) between the calculated adiabatic ionization potentials and experimental oxidation (anodic) potentials of hydrocarbons were obtained in terms of B3PW91 approximation.